Concurrency attacks

Abstract

Just as errors in sequential programs can lead to se-curity exploits, errors in concurrent programs can lead to concurrency attacks. Questions such as whether these at-tacks are real and what characteristics they have remain largely unknown. In this paper, we present a preliminary study of concurrency attacks and the security implica-tions of real concurrency errors. Our study yields several interesting findings. For instance, we observe that the exploitability of a concurrency error depends on the du-ration of the timing window within which the error may occur. We further observe that attackers can increase this window through carefully crafted inputs. We also find that four out of five commonly used sequential defense mechanisms become unsafe when applied to concurrent programs. Based on our findings, we propose new de-fense directions and fixes to existing defenses. 1